Cynodon dactylon plant named ‘Plateau’

ABSTRACT

The new variety comprises a  Cynodon dactylon  plant named ‘Plateau’ exhibiting a low growing height and prostrate spreading habit making it suitable for wide landscape usage.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinct Cynodon dactylonvariety.

The new variety is the result of a spontaneous mutation of a common,unnamed, and unpatented couch grass (Cynodon dactylon) growing on theproperty of the inventor at Collaroy Plateau, New South Wales,Australia. The new variety was propagated vegetatively through fourgenerations. The varietal denomination of the new variety is ‘Plateau’.

There is an ongoing need worldwide, and in particular in the UnitedStates of America, for turf grass varieties which are hard wearing, lowin maintenance, which provide good ground cover, are of low growingheight with a prostrate spreading habit, high sward density, medium tolow seed head production and lustrous coloration. Such varieties findparticular use on golf courses, bowling greens, parks, playing fields,as well as in domestic and commercial settings.

The parent of ‘Plateau’, an unnamed couch grass seedling, is arepresentative example of generic couch grass widely grown and used indomestic lawns, in golf courses, and in parks. As described hereinafter‘Plateau’ is an advantageous turf grass species in many respects overand above commercial grass species, and common unnamed which grass isrepresented by the parent.

SUMMARY OF THE INVENTION

The new variety of Cynodon dactylon, ‘Plateau’, exhibits low growingheight, prostrate spreading habit, prostrate shoot growth, shortinternode length, high sward density, wide stolon to rhizome widthratio, and medium seed head frequency, amongst other characteristicsherein described which distinguish the subject variety from presentlyavailable commercial turf grass varieties.

Under wide climatic conditions, for example, in coastal areas ofCalifornia, inland areas and in temperate and less temperate conditions,green color quality, and good cover/sword density can be maintainedthroughout the year. The new variety is vegetatively propagated fromsod, plugs, tillers or stolons and rhizome pieces. Asexual propagationby rhizome and tillers in various commercial growing trials inNarrabeen, New South Wales, Australia has demonstrated that thecombination of characteristics of the new variety are transmittedthrough successive propagations.

The most similar variety known to the inventor is the variety ‘Riley'sSuper Sport’, the subject of U.S. Plant Pat. No. 1,181 issued Jan. 18,2000 which forms a dense turf of low growing height. Another comparatoris the variety ‘Greenlees Park’ which is a widely available commercialvariety of the same species and which is the parent of ‘Riley's SuperSport’. ‘Plateau’ differs from ‘Riley's Super Sport’ in that it has lessfrequent nodes, medium to low seed head frequency, longer leaves,narrower stolons and thicker rhizomes. ‘Plateau’ differs from ‘GreenleesPark’ in that is has a low growing height, prostrate shoot growth,shorter internode length, high sward density, wide stolon to rhizomewidth ratio, and medium to low seed head frequency.

BRIEF DESCRIPTION OF ILLUSTRATIONS

The accompanying illustrations show typical specimens of the vegetativegrowth of the new variety.

FIG. 1 shows a close up of a turf section and of isolated stolons of thenew variety with comparative varieties ‘Riley's Super Sport’ and‘Greenlees Park’, showing growth habit/turf appearance, node frequencyand stolon thickness.

FIG. 2 shows a replicated lateral extension rate trial, with plugs of‘Plateau’ (P), ‘Riley's Super Sport’ (R) and ‘Greenlees Park’ (GP)spaced in repeated sequence (4) along the plot, twenty-one days afterplanting. Long radiating stolons of ‘Plateau’ are clearly evident.

DESCRIPTION OF THE NEW VARIETY

The description of color is by reference to The Royal HorticulturalSociety Colour Chart. The plants described are about 13 months old.

The new variety has a prostrate (to 50 mm) spreading growth habit with arapid lateral extension rate (about 20 cm in twenty one days) and highnode density.

Leaf blades are of green coloration (near 147A), the leaf length isshort, having a mean length of about 20.8 mm, the leaf width is narrow,having a mean width of about 2.3 mm, and the mean leaf length:widthratio is about 9.1:1. The ligule has a dense row of short hairs about0.2 to 0.5 mm long on a membranous rim with longer hairs about 1.0 to1.5 mm long at each end. The blades are flat linear-triangular about 2.0to 2.5 mm long, about 1.- to 2.0 mm wide, pointed, glabrous and sparselypubescent, minutely scabrous on the margin. Auricles are absent andvernation conduplicate. The sheath is glabrous and sparsely pubescent.

Stolons of ‘Plateau’ are red/purple (near 60C). They are of highdensity, with a short internode length having a mean of node frequencyof about 5 per cm length. Stolons are of medium thickness, having a meanthickness of about 1.06 mm. Stolons are strongly prostrate, andgenerally form about 30 to 50 mm long.

The new variety is strongly rhizomatious with a mean width of about 1.9mm, and a narrow stolon to rhizome thickness ratio having a mean ofabout 1.8 mm.

Culms are smooth, slender decumbent to semi-erect, about 20 to 50 mmlong, about 1.0 to 2.0 mm wide, and colored red/purple (near 60C).

Inflorescence of the new variety is digitate of 2 to 7 spikes, linearabout 15 to 30 mm long and about 1.0 to 1.5 mm wide; spikelets broad,laterally compressed to about 3.0 mm long and about 2.0 mm wide; glumesacuminate about 1.0 to 2.5 mm long; lemma keeled, mucronate about 1.5 to3.0 mm long, ciliolate along the keel; sterile rachilla extension 0.5 to1.5 mm long, sometimes topped with a vestigial spikelet, and the anthercolor is red/purple (near 74D).

Seed head frequency of the new variety is low to medium having a mean ofabout 9.2 per 100 cm².

Winter growth of ‘Plateau’ is comparable with other known Cynodondactylon varieties.

The new variety is vegetatively propagated from sod, plugs or stolon orrhizome pieces, as mentioned presiously. It performs best in sun, butalso grows well in shade. The variety has an easily controllable matdensity, and is hard wearing. As a consequence, the variety isresponsive to mowing management in order to provide, for example, a firmsurface for use such as in bowling greens and golf tees, or a softsurface for use such as in parks, in domestic situations, or on golffairways.

Under conditions of very limited water availability, the new varietyrevives quickly on the application of water.

The turf formed from the new variety is accordingly suitable forsituations requiring a durable, high quality lawn or turf that istolerant to heat and drought stress. As mentioned previously, suchapplications include bowling greens, sport stadia, golf courses, parks,public planting areas and domestic lawns.

In general, Cynodon dactylon ‘Plateau’ has been observed to be no moresusceptible to pests and diseases than other commercial varieties. Inparticular, ‘Plateau’ has been observed to display delayedsusceptibility to the fungal disease syndrome of ‘Helminthosporium’(Bipolaris and Dreschlera spp.). Fungal diseases of this nature areinfluenced by climatic conditions and are not usually persistent.‘Dollar Spot’ (Lanzia spp. and others) and ‘Spring Dead Spot’(Leptosphaeria namari and L. korrea) have not been observed on ‘Plateau’and may indicate strong resistance to these diseases.

Common pests of Cynodon dactylon species such as scarab beetles,grass-eating caterpillars, mites, flea beetle and tip maggot has beenobserved on ‘Plateau’. The subsequent plant injury and susceptibilityobserved is no greater in comparison to that on other varieties ofCynodon dactylon.

The accompanying illustration serves to show the distinctive features ofthe new variety. As can be seen from FIG. 1 the new variety has aprostrate growth habit which can be finely cut, such as to about 2 to 3mm height, thus allowing a dense mat of prostrate growth habit for useas a putting green, bowling surface or other such surface, or thevariety may be cut at a greater height to provide a durable trafficsurface, such as a golf fairway, verge of a bowling green and many othersuch applications. FIG. 1 shows the high node frequency, as depicted byshort internode length, long spreading stolons. The new variety is a lowlying grass and contrasts with the marked vertical extension of thecomparative variety ‘Greenlees Park’. The new variety is clearlydistinguished from the comparative varieties ‘Riley's Super Sport’ onthe basis of the internode length, longer leaf length and long spreadingstolons. The new variety is clearly distinguished from the comparativevariety ‘Greenlees Park’ on the basis of greater node frequency, shorterleaf length, prostrate spreading growth habit, and dense growth habit.The principal features of prostrate and dense habit, long spreadingstolons and short internode length are clearly observable.

To further illustrate the differences between the new variety ‘Plateau’and the comparative varieties ‘Riley's Super Sport’ and ‘GreenleesPark’, tests were conducted at the Narrabeen, New South Wales,Australia, RSL Bowling Green trial site in the summer of 1998/1999.Twelve plots measuring 2×1 m were planted in the field in loamy sand ofuniform texture, using four replicates of the new variety ‘Plateau’, andthe two comparator varieties ‘Riley's Super Sport’ and ‘Greenlees Park’.This plot order was replicated four times. One hundred stolons were usedto establish individual trial plot replicates.

Irrigation and fertilisation was carried out as required at standardrates. Irrigation of the trial plots was by daily hand watering in theinitial two weeks of grass establishment. Following this the plots werewatered twice per week to soil field capacity using perforated,detachable above ground aluminum pipes (Perf-O-Rain). Irrigation wassuspended at times when rainfall was sufficient to sustain developmentof the grasses.

All fertilization was by controlled release fertilizer applied at therate of 70 grams/m² to provide 8.6 grams elemental nitrogen per squaremeter, 4.13 grams elemental phosphorous per square meter, and 7.42 gramselemental potassium per square meter. Four applications of thisfertilizer were made at this rate during the trial period. These were inJanuary, March, and November 1998 and in February 1999.

Two insecticide treatments were applied in the growing season.Insecticide treatments were as follows: February and April 1998,Chlopyrofos at 7 ml per 100 m² to control grass eating caterpillars;December 1998, “Rogor” as dimethoate at 4 mg per 100 m² to controlBermuda (Couch) grass tip maggot; and February 1999, “Dursban” aschlorpyrofos at 7 mg per 100 m² to control grass eating caterpillars.

No mowing was carried out. Measurements were taken from 100 randomsamples for unmown height, leaf length and width, node frequency, twentyfive samples for rhizome/stolon thickness, angle of shoot emergence andtwelve samples were taken for group counts for seed head density. Theresults of these comparative test evaluations are shown in Table 1. Alsoshown in Table 1 and depicted in FIG. 2 is a lateral extension ratetrial of four repeated spaced replicates of ‘Plateau’, ‘Riley's SuperSport’ and ‘Greenlees Park’.

Statistical differences among the cultivars were determined according tostandard statistical tests.

‘Plateau’ has a prostrate spreading habit compared with the veryprostrate habit of ‘Riley's Super Sport’ and the vertical growth habitof ‘Greenlees Park’. Node density of ‘Plateau’ was high, having a meannode frequency (number/cm) of 5.03, compared with 6.6. for ‘Riley'sSuper Sport’ and 4.30 for ‘Greenlees Park’. High node density of the newvariety, combined with long leaf length and thin stolon width, comparedto the comparative variety ‘Riley's Super Sport’ results in a highdensity of ground cover. Coupled with a prostrate growth habit aparticularly good density and ground cover results.

The mean uncut sward height is 35.09 mm, compared with a mean of 30.01for ‘Riley's Super Sport’ and 301.63 for ‘Greenlees Park’. The mean leaflength (20.83 mm), leaf width (2.31 mm), and mean leaf/width ratio (9.12mm) shown in Table 1 for ‘Plateau’ clearly differentiates ‘Plateau’ fromthe varieties ‘Riley's Super Sport’ and ‘Greenlees Park’. Thiscombination of characteristics associated with high density and shortinternode length provides a high density turf of pleasant appearancehaving excellent ground cover and minimal vertical growth as previouslydescribed.

Seed head production of ‘Plateau’ was low to very low, having a meannumber of seed head density (number/100 cm²) of 9.7, compared with amean seed head density of 12.33 for ‘Riley's Super Sport’ and 3.83 for‘Greenlees Park’. The low seed head production of ‘Plateau’ gives anattractive appearance of the turf and decreases the need for mowing toremove seed heads. Where seed heads are allowed to produce flowers, theanther color is red/purple (near 74D).

The subject variety has additional characteristics of long spreadingstolons (mean width 1.06 mm), strong rhizomiticity (mean width 1.932mm), medium leaf length (mean 20.83 mm), and narrow leaf width (mean2.037 mm). These features additionally characterise the new variety fromother Cynodon dactylon varieties.

The subject variety contains other standard charcteristics of Cynodondactylon varieties which do not distinguish it from, and are common to,other Cynodon dactylon varieties, including culm, glume, sheath andlemma.

The new variety ‘Plateau’ as previously described is a spontaneousmutation of an unnamed common couch grass (Cynodon dactylon) growing onthe property of the inventor, Peter Brown, as Collaroy Plateau, NewSouth Wales, Australia in 1975. The unnamed parent variety wascharacterised by upright shoot growth, thick stolons, long internodelength, long leaf length and high seed head frequency. ‘Plateau’ differsfrom the parent variety by the features of low growing height, prostrateshoot growth, short internode length, narrow stolon to rhizome widthratio and low to very low seed head frequency as described herein.Vegetative propagation of the mutant stolons was first carried out in1975 and continuous propagation and selection was carried out giving theresultant ‘Plateau’ variety.

‘Plateau’ is a turf grass variety of Cynodon dactylon having theaforementioned features which distinguish it from the varieties ‘Riley'sSuper Sport’ and ‘Greenlees Park’, and common couch grass varietiesdescribed.

TABLE 1 *‘Riley's Super *‘Greenlees ‘Plateau’ Sport’ Park’ UNCUT SWARD(mm) Mean  35.09 30.01  301.63  std deviation 1.53 1.57 13.80  LSD/sig2.65 P ≦ 0.01 P ≦ 0.01 LEAF LENGTH (mm) Mean  20.83  13.95  75.31  stddeviation 2.48 2.39 6.50 LSD/sig 1.40 P ≦ 0.01 P ≦ 0.01 LEAF WIDTH (mm)Mean 2.31 2.26 2.39 std deviation 0.23 0.25 0.35 LSD/sig 0.09 ns ns LEAFLENGTH/WIDTH RATIO Mean 9.12 6.24 31.81  std deviation 1.44 1.28 2.71LSD/sig 0.63 P ≦ 0.01 P ≦ 0.01 NODE FREQUENCY (number/cm) Mean 5.03 6.604.30 std deviation 1.46 1.19 0.70 LSD/sig 0.38 P ≦ 0.01 P ≦ 0.01 RHIZOMETHICKNESS (mm) Measured 1 cm below soil surface Mean 1.93 1.62 1.18 stddeviation 0.30 0.36 0.20 LSD/sig 0.21 P ≦ 0.01 P ≦ 0.01 STOLON THICKNESS(mm) Mean 1.06 1.29 1.00 std deviation 0.17 0.25 0.29 LSD/sig 0.17 P ≦0.02 ns RHIZOME/STOLON THICKNESS RATIO Mean 1.83 1.29 1.26 std deviation0.33 0.33 0.45 LSD/sig 0.26 P ≦ 0.01 P ≦ 0.01 SEED HEAD DENSITY(number/100 cm²) Mean 9.17 12.23  3.83 std deviation 1.34 1.50 0.94LSD/sig 3.71 ns P ≦ 0.01 SHOOT EMERGENCE ANGLE O° = vertical, 90° =horizontal Mean 79.96° 85.00° 71.04° std deviation  2.130 1.93 4.51LSD/sig 0.90 P ≦ 0.01 P ≦ 0.01 LEAF COLOR (RHS 1995) 147A 137A 137BLATERAL EXTENSION RATE (cm)* Measured twenty one days of planting Mean20   15.4  18.5  std deviation 7.9  5.28 4.22 LSD/sig 3.28 P ≦ 0.01 NS*Measured on pioneer stolons growing from 100 mm diameter plugs plantedon bare ground at 1.5 m intervals. From the centre of each plug theareas was divided into eight equal 45°sectors. The longest stolon ineach sector was measured. Four replicate plugs of each grass wereplanted.

I claim:
 1. A new distinct plant of Cynodon dactylon plant named‘Plateau’, substantially as described and illustrated.